Surgical wound infections are an important cause of morbidity, mortality, and excess hospital costs. Surgical wound infections are the second most frequently found nosocomial infection overall, and among surgical patients, surgical site infections are the most common nosocomial infection site. Three factors contribute to the risk of developing a surgical wound infection: 1) the amount of and type of microbial contamination of the wound; 2) the condition of the wound at the end of the operation; and 3) host susceptibility, that is, the patient's intrinsic ability to deal with microbial contamination. In immuno-compromised patients, a greater tendency for infections caused by resident skin bacteria exists. Surgical site infections, which may, for the most part be benign in normal patients, may be fatal to the immuno-compromised. It is therefore a goal of the present invention to control resident skin bacteria at the site of an invasive surgical procedure.
Illustrating the gravity of the problem, the Centers for Disease Control and Prevention reported the number of sepsis cases tripled from 1979 to 1992 due to increased invasive procedures in older and immune-suppressed patients. In the U.S., every year roughly 500,000 people acquire sepsis and 175,000 die. One conservative estimate of the average cost of a surgical site infection, as determined on the basis of an average extra length of hospital stay of five days is $7,500. In addition to these direct costs, there are significant consequences such as lost productivity due to missed workdays, emotional trauma inflicted on patients and health provider as a result of the development of surgical site infections, patient dissatisfaction with the outcome of the operation, and the fear of malpractice on the part of the health care provider.
In order to reduce the risk of wound infection and maximize primary healing, a preoperative skin preparation seeks to create a clean operative field while minimizing damage to the skin. The preoperative skin preparation reduces the risk of postoperative wound infection by removing soil and transient microorganisms from the skin, by reducing the resident microbial count to subpathogenic amounts in a short period of time, and by inhibiting rapid rebound growth of microorganisms.
The surgical site preparation objectives (scrub, antimicrobial painting of skin and draping of the surgical site) are to remove dirt, skin oil and microbes from the skin while also providing a barrier against microbial migration into the incision. It is desired these objectives be achieved with the least amount of skin irritation. It is suggested that the agent used for scrubs and painting be a broad-spectrum antimicrobial, provide residual protection, and be nontoxic. An ideal antiseptic solution leaves a residue on the skin surface that continues to exert antimcrobial activity throughout the surgical period. This residual film should inhibit recolonization of the skin flora from environmental contact, from centripetal spread of microbes originating outside the field of prepared skin, and from the resident flora within the prepared field.
Many of the common surgical skin preparation protocols employ a topical application of an antimicrobial agent. Typically, topical application of antimicrobial agents is accomplished using, for example, lotions, ointments, and preoperative skin preps. The initial application of the antimicrobial agent, however, frequently does not impart the desired antimicrobial properties and requires continued application. During a surgical procedure the antimicrobial agent may also be removed by the action of blood, biological fluids and saline washes applied to the site. These two problems may lead to a rebound of the microorganism flora, and result in postoperative wound infection. It is therefore advantageous to have a one-step antimicrobial delivery system capable of maintaining an aseptic environment at the surgical site before and following the surgical procedure.
Other surgical skin preparation protocols employ a preopertive scrub, paint and drape procedure. The preoperative scrub is generally performed with antibacterial compounds such as povidone-iodine, chlorhexidine and hexachlorophene for varied periods of time (2-10 minute scrubs). The skin is then painted (or sprayed) with the antimicrobial. Povidone-iodine preparations are most widely used. 3M Corporation has developed a one-time skin preparatory solution, DURAPREP.TM. (U.S. Pat. No. 4,584,192), that is painted on and dries within 2 minutes. Although skin scrubs and painting demonstrate initial microbial inhibtion, none have proven efficacious for longer surgical time periods.
Adhesive-backed film incise drapes are often applied after conventional skin preparation, and surgical incisions are made through the drape. Adhesive drapes have proven to be effective in preventing resident flora from migrating into the wound as long as they are not peeled back from the wound edges or loosened by trapped fluids or air. The intrinsic benefits and antimicrobial effectiveness of the traditional adhesive-backed incise drape, however, are negated by its problems with creasing, wrinkling, and separation from the wound edge.
Eliminating the current practice of using separate antimicrobial preparations and adhesive incise drapes would cut down on the cost of materials, reduce prep time, and decrease the time needed for anesthesia. A combination antimicrobial preparation and incise drape that could be uniformly applied would benefit the patient by reducing the incidence of infection, thereby improving the chances of successful surgery and limiting prolonged post-operative hospital stay due to nosocomial surgical infection.
Polyvinylidene fluoride (hereinafter occasionally abbreviated as PVDF) is a mechanically tough thermoplastic that readily and stably polymerizes without low molecular weight contaminants or chemical stabilizers. PVDF is approved for use by the Food and Drug Administration for repeated contact with food and by the National Sanitation Foundation under Standard 61 for high purity water systems. KYNAR.RTM. brand PVDF homopolymers and copolymers (Elf Atochem ATO, Philadelphia, Pa.) are also in compliance with US Pharmacopeia Classification VI. Materials safety sheets (MSDS) provided with the KYNAR.RTM. products indicate 100% of the respective polymer compound to be present with no detectable impurities.
The present invention addresses the problems in the art with an improved PVDF-based film-forming composition and one-step method of use for a combination preoperative skin preparation and surgical incise drape. No one before the present inventors realized and demonstrated that PVDF-based coatings could provide an excellent combination preoperative skin preparation and surgical incise drape as provided herein.